The aim of our research work was to study the role of the oil radish catch crop (Raphanus sativus var oleiformis Pers) as second crop or stubble crop for green manuring in winter wheat-winter barley-maize crop rotation. The oil radish was grown after the harvest of winter barley in the crop sequence. The green biomass (t ha-1), nitrogen (N) content in dry material (g kg-1) of catch crop and the N (kg ha-1) taken up by the catch crop were investigated for six years (1997-2002). The main goal was to measure the amount of remained N in the soil left by the main crop (WB) and the amount of N taken up by the oil radish catch crop. The maximum N uptake was about 120 kg ha-1 calculated on the average of the years but in the rainy 1998 the N removal reached the 200 kg ha-1 N. On the basis of the N balance calculation it is proved that incorporation of the catch crop in the crop sequence, the risk of N leaching diminishes, or can be minimal even if the level of N input is high, because the N removal of green biomass retains N in the soil and this way N turnover of the crop rotation remains balanced.